[PATCH 1/2] ARM: meson: Adding support to retrieve serial and SoC revision

Hi all,

2016-02-17 21:34 GMT+01:00 Carlo Caione [off-list ref]:

On Wed, Feb 17, 2016 at 6:28 PM, Romain Perier [off-list ref] wrote:

quoted

This path adds support to get the revision and the serial of the running
SoC, on Meson8. On these plaforms, these informations can be found into

no Meson8b or Meson6?

Well, I only tested on Meson8b, I don't know if it works in the same
way on older Meson, however I can take a look to the vendor kernel
probably...

quoted

CBUS registers. To do so, we instanciate a syscon register, then create

What you mean with syscon register?

I mean that we use a syscon regmap to access these registers.

quoted

a soc_device, and finally we expose everything to the system.

Signed-off-by: Romain Perier <romain.perier@gmail.com>
---
 arch/arm/mach-meson/meson.c | 55 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/arch/arm/mach-meson/meson.c b/arch/arm/mach-meson/meson.c
index 4e23571..2816e30 100644
--- a/arch/arm/mach-meson/meson.c
+++ b/arch/arm/mach-meson/meson.c

@@ -13,8 +13,16 @@
  *
  */

+#include <linux/of_address.h>
 #include <linux/of_platform.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
 #include <asm/mach/arch.h>
+#include <asm/system_info.h>
+
+#define MESON_REVISION_REG (0x45c)

 static const char * const meson_common_board_compat[] = {
        "amlogic,meson6",

@@ -23,7 +31,54 @@ static const char * const meson_common_board_compat[] = {
        NULL,
 };

+static void __init meson_init_machine(void)
+{
+       struct soc_device_attribute *soc_dev_attr;
+       struct soc_device *soc_dev;
+       struct regmap *hwrev;
+       unsigned int val;
+       int ret;
+
+       hwrev = syscon_regmap_lookup_by_compatible("amlogic,meson8b-hwrev");

Is this specific only for Meson8b?

For now, yes. However, As I said, I can to do something generic. What
do you think ?

quoted

+       if (IS_ERR(hwrev)) {
+               pr_err("hwrev node not found\n");
+               return;
+       }
+
+       soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+       if (!soc_dev_attr)
+               return;

Missing blank line

quoted

+       ret = regmap_read(hwrev, 0, &val);
+       if (ret < 0) {
+               pr_err("Could not get SoC id\n");

kfree(soc_dev_attr)

quoted

+               return;
+       }
+       system_serial_high = val << 24;
+
+       ret = regmap_read(hwrev, MESON_REVISION_REG, &val);
+       if (ret < 0) {
+               pr_err("Could not get SoC revision\n");

ditto

quoted

+               return;
+       }
+       system_rev = val == 0x11111111 ? 0xA : 0xB;
+
+       soc_dev_attr->family = "Amlogic Meson";
+       soc_dev_attr->revision = kasprintf(GFP_KERNEL, "0x%x", system_rev);
+       soc_dev_attr->soc_id = kasprintf(GFP_KERNEL, "0x%x", system_serial_high);
+
+       soc_dev = soc_device_register(soc_dev_attr);
+       if (IS_ERR(soc_dev)) {
+               pr_err("Could not register soc device\n");
+               kfree(soc_dev_attr);

leaking soc_dev_attr->revision and  soc_dev_attr->soc_id also any
reason why you are not kasprintf-ing also family?

My problem is that I cannot use a devm allocation there, right ? I
mean I have no device... Well, I will think about it.

quoted

+               return;
+       }
+
+       pr_info("Amlogic Meson SoC Rev%X (%X:%X)\n", system_rev, system_serial_high, system_rev);
+       of_platform_populate(NULL, of_default_bus_match_table, NULL, soc_dev);

Compiling I got:

  CC      arch/arm/mach-meson/meson.o
arch/arm/mach-meson/meson.c: In function 'meson_init_machine':
arch/arm/mach-meson/meson.c:77:63: warning: passing argument 4 of
'of_platform_populate' from incompatible pointer type
  of_platform_populate(NULL, of_default_bus_match_table, NULL, soc_dev);
                                                               ^
In file included from arch/arm/mach-meson/meson.c:17:0:
include/linux/of_platform.h:71:12: note: expected 'struct device *'
but argument is of type 'struct soc_device *'
 extern int of_platform_populate(struct device_node *root,
            ^

Ah, good catch ! I build everything using yocto, so I did not see
these warnings ^^

quoted

+}
+
 DT_MACHINE_START(MESON, "Amlogic Meson platform")
+       .init_machine   = meson_init_machine,

Uhm, you are assuming that this code is valid for Meson8, Meson8b and
also Meson6. Are you sure about that?

No, you're right.

Thanks,
Romain